This thesis presents the research and reflections on the development of an ontology based application dedicated to e-recruitment in the field of Information Technologies’ staffing services, and especially e-recruitment using Social Web platforms as sources for candidates. This application, called Combine, essentially aims to optimize and enhance the field recruiters’ Computer-Mediated Communication (CMC) and uses concepts from the emerging technological paradigm that the Semantic Web represents. Rarely discussed in a CMC perspective, this submission therefore proposes to study the communications issues related to this new paradigm. It presents the main concepts, as the notion of ontology, which involves the formal modeling of knowledge, and outlines the development case of Combine. It describes how the system was designed, from the requirements analysis to the prototype evaluation, revealing the concerns, the constraints and the opportunities met along the way. After this examination, the thesis stretches out to critically assess Combine’s potential to optimize the CMC in the targeted field of activity. In the end, the thesis conveys a rather favorable outcome concerning the positive perception of the field recruiters about using this type of application, and also concerning the promising benefits in Human-Computer Interactions (HCI). However, it mentions as well the exacerbation of the problem called "ontological commitment", which is to consider when building ontologies that model social objects such as those which the world of recruitment is made of.